Expandable reverse shoulder trial

Abstract

An expandable shoulder trial for a reverse shoulder system is described. The trial includes a rotatably adjustable insert housed within a humeral cup. The insert has a proximal end and a distal end, the proximal end having a concave recess therein adapted to receive a glenosphere prosthesis. The distal end of the insert includes a shaft, the shaft having a helical groove disposed on at least a portion thereof. A distal end of the humeral cup is inserted in a humeral stem. The humeral cup has a proximal end including a recess therein, the recess defined by a circular wall. A guide pin protrudes from the circular wall and is adapted to engage the helical groove of the shaft of the insert. The proximal end of the insert may rotate along an axis toward the proximal end of the humeral cup and along the same axis away from the proximal end of the humeral cup.

Description

FIELD OF THE TECHNOLOGY[0001]The present invention relates to an expandable reverse shoulder trial for reverse shoulder athroplasty (RSA), and in particular it relates to such a trial including an insert that rotatably engages a humeral cup.BACKGROUND OF THE INVENTION[0002]The successful outcome of RSA depends greatly on proper soft tissue tension. Since the rotator cuff is either absent or severely compromised and irreparable, the stability of the shoulder joint comes from significant deltoid tension holding the ball and socket joint together.[0003]Existing reverse shoulder systems require a surgeon to pick a trial liner and reduce the shoulder joint with that liner assembled into a humeral cup. If the correct liner is chosen, the soft tissue tension is significant, requiring the surgeon to apply extreme force to the humerus and surrounding soft tissues to reduce the joint. If no additional damage is done during this reduction process, the joint must then be dislocated to allow the...

AI Technical Summary

Benefits of technology

[0033]In one aspect of a method of the present invention, the insert may be rotated in the first direction approximately 60° to reduce the distance between the proximal end of the humeral cup and the proximal end of the insert approximately 2 mm. Preferably, the insert includes an incremental stopping portion every 60° along the guide portion or cam-track of the shaft portion of the insert. As the insert is rotated in either a first or second direction the guide pin of the humeral cup may engage an incremental stopping portion of the

Problems solved by technology

Preferably, the expandable trial also decreases the size and cost of the overall instrument set, since only one trial per glenosphere diameter is generally

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